Golf is a notoriously difficult game to play. In a golf swing, numerous factors affect whether the golf ball will be struck properly. The movement of the hands, feet, elbows, shoulders, hips, knees and feet all must combine to move the golf club in the proper swing plane. Only by learning to control these factors in each and every swing can the golfer consistently hit good golf shots. It is the job of a teaching professional to teach a golfer to control these factors in a coordinated sequence of action. When coordinated properly, the golfer's swing is said to be "In Line".
In a proper In-Line golf swing, there should be little to no torque created around the longitudinal axis of the club. If such a torque is created, it shows that the golfer is not using the correct wrist and shoulder movement, and thus is not forming a proper swing plane.
Numerous devices have been developed which are intended to teach a proper golf swing. However, none of these devices teach a proper swing plane by teaching the golfer to minimize the torque created around the longitudinal axis of the club.